I don't speak German fluently, so Ill write my comment in english to make it a bit easier on myself
I first played the second mode. At first I didnt realise you could use wasd. One I figured that out I realised that the enemies always respawn in the same spot, and that they slowly converge to one point if you can get them bunched up. So I isolated one enemy and farmed point on it. I ended up dying due to going over the edge of the screen (I hadnt figured out that was possible yet, I scored somewhere in the 700s).
The second one I didnt try as long, the movement wa frustratingly fast, and since I already knew space invaders, it wasnt very interestign to paly either. On a final note, I wanted to say that I liked the story.